The present invention is related to a heat exchanger tube, and particularly to a tube-fin heat exchanger tube and method of making the same.
Heat exchangers incorporating a plurality of tubes through which a hot fluid circulates between upper and lower tanks or headers are well known. Unfortunately, it is also known that the brazed or soldered joints between these tubes and their associated heat dissipating fins present a continual service problem. A single defective joint can cause a leakage problem which requires the removal of the heat exchanger from its associated power plant for complicated and expensive repair. In order to avoid such potential leakage problems the joints are frequently overbrazed, and this can result in partial blocking of the fluid flow and impairment of the overall efficiency of the heat exchanger.
One known heat exchanger employs a plurality of tubes with a cylindrical configuration with integral spiral fins formed thereon by an extrusion process. Still another heat exchanger utilizes cylindrical tubes with folded fins which are produced first by fluting the tube, and then by twisting and compressing it. Manufacturing complexities are involved with the production of these tubes, and they are limited to certain dimensions because of the method of making them. For example, both of these tubes are undesirably restricted to cylindrical shapes.
Another heat exchanger tube, namely that disclosed in U.S. Pat. No. 3,119,446 issued Jan. 28, 1964 to G. Weiss, embodies a facing pair of symmetrical corrugated sheets which are interconnected at both sides thereof by complex intermeshed edge portions. Such expensive construction undesirably provides equal amounts of exposed surface area on the inside and on the outside of the tube, a tortuous route for fluid travel internally thereof, and extended regions of potential leakage at the joints thereof.